enabling Rewards from panel should have waiter message when opting in

[LaurenWags]

Description

Similar to issue reported in #1099. If you are using a fresh profile and you click on the BAT logo and are prompted to join Brave Rewards, when you click 'Join Rewards' there is a lag. It would be helpful if this had a similar waiter message as when opting in from chrome://rewards. I'm not sure if the exact same one is appropriate, users might not know what 'creating wallet' means here.

Steps to Reproduce

1. Clean profile.
2. Click on BAT logo in URL bar.
3. On Brave Rewards panel click on JOIN REWARDS

Actual result:

Note lag, doesn't seem like anything is happening.

Expected result:

Waiter message similar to when opting in from chrome://rewards page

Reproduces how often:

easily

Brave version (chrome://version info)

Brave	0.55.12 Chromium: 70.0.3538.45 (Official Build) beta(64-bit)
Revision	cbdc32e4334458954e9def214d7e5fa1ca1960eb-refs/branch-heads/3538@{#830}
OS	Mac OS X

Reproducible on current release:

• Does it reproduce on brave-browser dev/beta builds? yes
• Does it reproduce on browser-laptop? n/a

Website problems only:

• Does the issue resolve itself when disabling Brave Shields? n/a
• Is the issue reproducible on the latest version of Chrome? n/a

Additional Information

cc @NejcZdovc @jenn-rhim

[srirambv]

Reproduced on Linux as well

[GeetaSarvadnya]

The referenced issue #1838 is still reproducible on Dev Build version 0.57.3. This issue is not there on Release build 0.55.20.

[NejcZdovc]

#1838 was not included in 0.57.3

[kjozwiak]

Waiting for #1838 to be fixed as it's reproducible under 0.55.21 Chromium: 70.0.3538.77 (Official Build) (64-bit) as well. Once #1838 has been resolved, this can be verified as well.

[LaurenWags]

Verified passed with

Brave	0.56.7 Chromium: 70.0.3538.77 (Official Build) beta(64-bit)
Revision	0f6ce0b0cd63a12cb4eccea3637b1bc9a29148d9-refs/branch-heads/3538@{#1039}
OS	Mac OS X

Verification Passed on

Brave	0.56.7 Chromium: 70.0.3538.77 (Official Build) beta (64-bit)
Revision	0f6ce0b0cd63a12cb4eccea3637b1bc9a29148d9-refs/branch-heads/3538@{#1039}
OS	Windows

Verification Passed on

Brave	0.56.8 Chromium: 70.0.3538.77 (Official Build) (64-bit)
Revision	0f6ce0b0cd63a12cb4eccea3637b1bc9a29148d9-refs/branch-heads/3538@{#1039}
OS	Linux